Prevention or remediation composition for dementia or depression

ABSTRACT

Compositions containing one or more kinds of essential amino acids other than leucine and not less than 35 mol % of leucine, relative to the total content of essential amino acids, are useful for preventing or improving dementia or a depressive state, in particular, a depressive state caused by stress, have high safety, and can be continuously ingested or administered.

CROSS REFERENCES TO RELATED APPLICATIONS

This application is a continuation of International Patent ApplicationNo. PCT/JP2017/033174, filed on Sep. 8, 2017, and claims priority toJapanese Patent Application No. 2016-176295, filed on Sep. 9, 2016, andJapanese Patent Application No. 2016-178739, filed on Sep. 13, 2016, allof which are incorporated herein by reference in their entireties.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to compositions for preventing orimproving dementia or a depressive state, in particular, a depressivestate caused by stress. The present invention also relates to methodsfor preventing or improving dementia or a depressive state, inparticular, a depressive state caused by stress.

DISCUSSION OF THE BACKGROUND

With the recent rapid increase in the elderly population, the number ofpatients with dementia has increased rapidly, and it has been reportedthat the population with dementia reached 8.4% of the population ofthose aged 65 or over in 2015.

According to the Ministry of Health, Labor and Welfare, in Japan,dementia is defined to mean “a state in which various mental functionsthat once developed normally after the birth have chronically declinedand disappeared to the extent that daily life and social life cannot bemanaged”.

Dementia includes dementia caused by various diseases such asAlzheimer-type dementia, frontotemporal dementia (Pick disease etc.),Lewy body dementia, and cerebrovascular dementia. While aging is thegreatest risk factor, its cause is often unclear.

However, in any type of dementia, core symptoms such as memory disorder,disorientation and the like, and behavioral and psychological symptomssuch as behavior abnormality, mental symptoms and the like are commonlyobserved, and progression of symptoms has serious effects such asincreased burden of nursing care and the like for not only patients butalso their families.

Currently, acetylcholinesterase inhibitors such as donepezilhydrochloride, and NMDA (N-methyl-D-aspartate) receptor antagonists suchas memantine have been approved as therapeutic drugs for dementia.However, these therapeutic drugs for dementia are basically forAlzheimer-type dementia, are symptomatic treatment drugs, and can merelysuppress progression of the symptoms somewhat.

Regarding the prevention of dementia, the importance of meal andexercise is known.

Regarding meals, the effectiveness of antioxidants such as vitamin C,vitamin E, β-carotene and ω-3 long-chain unsaturated fatty acids hasbeen reported, and the effects of ingestion of ω-3 long-chainunsaturated fatty acid, melatonin and tryptophan on mild cognitiveimpairment of the elderly people have been studied (see Angro FoodIndustry Hi-Tech 22 (4) 23-24 (2011), which is incorporated herein byreference in its entirety). Furthermore, reports suggest the effect ofL-arginine and lysine on Alzheimer-type dementia (see The AmericanJournal of Medicine 108 (5) 439 (2000 Apr. 1) and NeuropsychiatricDisease and Treatment 6 707-710 (2010), both of which are incorporatedherein by reference in their entireties).

Regarding exercise, it has been found that an increase in cerebral bloodflow due to exercise can improve physical activity and preventAlzheimer's disease.

However, some of the above-mentioned ingredients ingested in meals donot have sufficient preventive effect against dementia, and many requirefuture verification of the effectiveness.

Furthermore, some middle-aged and elderly people who have an increasedrisk of developing dementia often have difficulty in exercising due todisease or the like, or may have difficulty, due to a decline ofphysical function, in continuing exercise for prevention of Alzheimer'sdisease.

Therefore, it is difficult to say that a preventive drug having aneffective preventive effect on dementia, having high safety and capableof continuous ingestion, or a therapeutic drug capable of improvingdementia has been obtained.

Depressive state or depression refers to a situation in which the moodis depressed to dislike activity, due to which thought, behavior,emotion, and happiness are influenced.

Many depressive states are caused by various stresses, for example, jobproblems such as job loss, career change, and human relations at home orworkplace. It is also known to be sometimes caused by endocrine diseasessuch as hypothyroidism, diseases such as diabetes, cancer, sleep apneasyndrome, and medicaments such as interferon preparation, corticosteroiddrug.

A temporary depressive state can be improved by overcoming the stresscausing the state. Thus, a depressive state or depression is notgenerally treated with an antidepressant and the like.

However, when stress is a serious one that cannot be solved easily andcontinues for a long time, it may progress to a pathological depressivestate such as clinical depression.

Furthermore, depression is a symptom that appears as one of thebehavioral and psychological symptoms of dementia (BPSD). It is alsoknown that a depressive state is a high risk factor of the onset ofdementia (see The British Journal of Psychiatry 202 177-186 (2013) andJournal of Affective Disorders 202 220-229 (2016), both of which areincorporated herein by reference in their entireties).

Accordingly, a composition for preventing or improving a depressivestate is desired, which is capable of preventing or improving adepressive state, in particular, a depressive state caused by stress,and has high safety.

SUMMARY OF THE INVENTION

Accordingly, it is one object of the present invention to m providenovel compositions for preventing or improving dementia, which have aneffective preventive or improving effect on dementia, are highly safe,and enable continuous ingestion.

It is another object of the present invention to provide novelcompositions for preventing or improving a depressive state, which canfavorably prevent or improve a depressive state, particularly adepressive state caused by stress, have high safety and permitcontinuous ingestion or administration.

It is another object of the present invention to provide novel methodsfor preventing or improving dementia by administering such acomposition.

These and other objects, which will become apparent during the followingdetailed description, have been achieved by the inventor's discoverythat compositions containing a high content of leucine, and one or morekinds of essential amino acids other than leucine have an effect ofimproving memory disorder and cognitive function, and are effective forpreventing or improving dementia.

Furthermore, the present inventor has found that a compositioncontaining a high content of leucine, and one or more kinds of essentialamino acids other than leucine has a preventive or improving effect on adepressive state, particularly, a depressive state caused by stress.

That is, the present invention provides the following.

(1) A composition for preventing or improving dementia, comprising oneor more kinds of essential amino acids other than leucine and not lessthan 35 mol % of leucine relative to the total content of essentialamino acids.

(2) The composition of (1), wherein the content of leucine is 35 mol %to 66 mol % relative to the total content of essential amino acids.

(3) The composition of (1) or (2), wherein one or more m kinds ofessential amino acids other than leucine are isoleucine, valine,threonine, lysine, methionine, histidine, phenylalanine, and tryptophan.

(4) The composition of (3), wherein a molar composition ratio of thecontent of each amino acid relative to the total content of essentialamino acids falls within the following numerical values:

leucine 35 mol % to 66 mol %

isoleucine 5 mol % to 15 mol %

valine 5 mol % to 15 mol %

threonine 7 mol % to 14 mol %

lysine 8 mol % to 16 mol %

methionine 2 mol % to 10 mol %

histidine 0.1 mol % to 3.5 mol %

phenylalanine 2.5 mol % to 8 mol %

tryptophan 0.1 mol % to 2 mol %.

(5) The composition of any of (1) to (4), wherein the compositionprevents or improves a memory disorder.

(6) The composition of any of (1 to (4), wherein the compositionsuppresses a decline of cognitive function or improves cognitivefunction.

(7) The composition of any of (1) to (6), wherein the composition is apharmaceutical product.

(8) The composition of any of (1) to (6), wherein the composition is afood.

(9) The composition of any of (1) to (8), wherein the dementia isAlzheimer-type dementia.

(10) A method for preventing or improving dementia, m comprisingingestion by or administration to a subject in need of prevention orimprovement of symptoms of dementia of an effective amount of acomposition comprising one or more kinds of essential amino acids otherthan leucine and not less than mol % of leucine relative to the totalcontent of essential amino acids.

(11) The method of (10), wherein a content of leucine is mol % to 66 mol% relative to the total content of essential amino acids.

(12) The method of (10) or (11), wherein one or more kinds of essentialamino acids other than leucine are isoleucine, valine, threonine,lysine, methionine, histidine, phenylalanine, and tryptophan.

(13) The method of any of (10) to (12), wherein the dementia isAlzheimer-type dementia.

(14) A composition for preventing or improving a depressive state,comprising one or more kinds of essential amino acids other thanleucine, and not less than 35 mol % of leucine relative to the totalcontent of essential amino acids.

(15) The composition of (14), wherein the content of leucine is 35 mol %to 66 mol % relative to the total content of the essential amino acids.

(16) The composition of (14) or (15), wherein one or more kinds ofessential amino acid other than leucine includes isoleucine, valine,threonine, lysine, methionine, histidine, phenylalanine, and tryptophan.

(17) The composition of (16), wherein a molar composition ratio of eachamino acid to the total content of the essential amino acids is withinthe following numerical range:

leucine: 35 mol % to 66 mol %

isoleucine: 5 mol % to 15 mol %

valine: 5 mol % to 15 mol %

threonine: 7 mol % to 14 mol %

lysine: 8 mol % to 16 mol %

methionine: 2 mol % to 10 mol %

histidine: 0.1 mol % to 3.5 mol %

phenylalanine: 2.5 mol % to 8 mol %

tryptophan: 0.1 mol % to 2 mol %.

(18) The composition of any of (14) to (17), wherein the depressivestate is a depressive state caused by stress.

(19) The composition of any of (14) to (18), wherein the composition isa pharmaceutical product.

(20) The composition of any of (14) to (18), wherein the composition isa food.

(21) A method for preventing or improving a depressive state, comprisingingestion by or administration to a subject in need of prevention orimprovement of a depressive state of an effective amount of acomposition comprising one or more kinds of essential amino acids otherthan leucine and not less than 35 mol % of leucine relative to the totalcontent of the essential amino acids.

(22) The method of (21), wherein the content of leucine is 35 mol % to66 mol % of the total content of the essential amino acids.

(23) The method of (21) or (22), wherein one or more kinds of essentialamino acids other than leucine include isoleucine, valine, threonine,lysine, methionine, histidine, phenylalanine, and tryptophan.

(24) The method of any of (21) to (23), wherein the depressive state isa depressive state caused by stress.

Effect of the Invention

According to the present invention, a composition for preventing orimproving dementia can be provided.

The composition for preventing or improving dementia of the presentinvention effectively prevents or improves memory disorders, is alsoeffective for the suppression or improvement of a decline of cognitivefunction, and particularly effective for preventing or improvingAlzheimer-type dementia.

Furthermore, the composition for preventing or improving dementia of thepresent invention is highly safe and suitable for continuous ingestionor administration.

According to the present invention, a composition for preventing orimproving a depressive state, which can favorably prevent or improve thedepressive state can be provided.

The composition for preventing or improving a depressive state of thepresent invention is particularly effective for preventing or improvinga depressive state caused by stress.

Furthermore, the composition for preventing or improving a depressivestate of the present invention has high safety and is suitable forcontinuous ingestion or administration.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention and many of the attendantadvantages thereof will be readily obtained as the same become betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings, wherein:

FIG. 1 shows age-related changes in the total number of entries into thearm in the group in which deionized water was orally administered toSAMP8 (SAMP8-vehicle) and the group in which the composition of Example1 was orally administered to SAMP8 (SAMP8-AL40) in the Y maze test inExperimental Example 1.

FIG. 2 shows the evaluation results of spatial working memory (shortterm memory) in the group in which deionized water was orallyadministered to SAMP8 (SAMP8-vehicle) and the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)in the Y maze test in Experimental Example 1. In the Figure, “P8” showsthe group in which deionized water was orally administered to SAMP8(SAMP8-vehicle), and “P8-AL40” shows the group in which the compositionof Example 1 was orally administered to SAMP8 (SAMP8-AL40). In theFigure, moreover, “*” shows that a significant difference was found atP<0.05 between the above-mentioned two groups, and “**” shows that asignificant difference was found at P<0.01 between the above-mentionedtwo groups.

FIG. 3 shows the time required for entry into the dark compartment(transfer latency time) in the first trial, the number of trialsrequired to make individuals stay in the light compartment for 120seconds (trials to criterion) in the first trial, and the ratio of thenumber of individuals that stayed in the light compartment for 120seconds in the second trial, in the group in which deionized water wasorally administered to SAMR1 (SAMR1), the group in which deionized waterwas orally administered to SAMP8 (SAMP8-vehicle) and the group in whichthe composition of Example 1 was orally administered to SAMP8(SAMP8-AL40) in the passive avoidance test in Experimental Example 1. Inthe Figure, “SAMP8” shows the group in which deionized water was orallyadministered to SAMP8 (SAMP8-vehicle). In the Figure, moreover, “*”shows that a significant difference from SAMR1 was found at P<0.05, and“***” shows that a significant difference from SAMR1 was found atP<0.005.

FIG. 4 shows the time of stay in the light compartment 3 days later(retention time) in the group in which deionized water was orallyadministered to SAMR1 (SAMR1), the group in which deionized water wasorally administered to SAMP8 (SAMP8-vehicle) and the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)in the passive avoidance test in Experimental Example 1. In the Figure,“SAMP8” shows the group in which deionized water was orally administeredto SAMP8 (SAMP8-vehicle). In the Figure, moreover, “**” shows that asignificant difference from SAMR1 was found at P<0.01.

FIG. 5 shows Klüver-Barrera staining image of a hippocampus section inthe group in which deionized water was orally administered to SAMR1(SAMR1), the group in which deionized water was orally administered toSAMP8 (SAMP8-vehicle) and the group in which the composition of Example1 was orally administered to SAMP8 (SAMP8-AL40) in Experimental Example1.

FIG. 6 shows the measurement results of the number of neurons in thehippocampus section in the group in which deionized water was orallyadministered to SAMR1 (SAMR1), the group in which deionized water wasorally administered to SAMP8 (SAMP8-vehicle) and the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)in Experimental Example 1. In the Figure, “SAMP8” shows the group inwhich deionized water was orally administered to SAMP8 (SAMP8-vehicle).In the Figure, moreover, “**” shows that a significant difference fromSAMR1 was found at P<0.01.

FIG. 7 shows the content of acetylcholine in the homogenate ofprefrontal cortex (PFC) in the group in which deionized water was orallyadministered to SAMR1 (SAMR1), the group in which deionized water wasorally administered to SAMP8 (SAMP8-vehicle) and the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)in Experimental Example 1. In the Figure, “***” shows that a significantdifference from SAMR1 was found at P<0.005.

FIG. 8 shows a stress load menu in Experimental Example 2.

FIG. 9 shows changes in the body weight of the mice in each group inExperimental Example 2.

FIG. 10 shows difference in the body weight of the mice in each groupbetween day 31 of rearing and the day when the rearing was started inExperimental Example 2.

FIG. 11 shows the measurement results of immobility time of each groupin the forced swimming test in Experimental Example 2. In the Figure,different letters of “a”, “b” and “c” show the presence of a significantdifference among the respective groups.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The composition for preventing or improving dementia of the presentinvention (hereinafter to be also referred to as “the composition fordementia of the present invention” in the present specification)contains one or more kinds of essential amino acids other than leucine(i.e:, one or more kinds selected from the group consisting ofisoleucine, valine, threonine, lysine, methionine, histidine,phenylalanine, and tryptophan), and not less than 35 mol % of leucinerelative to the total content of essential amino acids.

In the present specification, “dementia” refers to a condition in whichany of the symptoms of memory disorder, decline of cognitive function(orientation disorder), lower judgment and deficit in executive functionis presented as the core symptom, and also includes various behavioraland psychological symptoms of dementia (BPSD) such as depressive state,dependence, anxiety, aggressive behavior, hallucination, delusion, sleepdisorder, wandering and the like.

It also includes dementia caused by various diseases and lesions such asAlzheimer's disease, Frontotemporal lobar degeneration (Pick diseaseetc.), Lewy body disease, and cerebrovascular diseases.

The term “prevention of dementia” refers to suppression of the onset ofdementia showing the above-mentioned symptom or state, and “improvementof dementia” refers to reduction of the above-mentioned symptoms orconditions.

The composition for preventing or improving a depressive state of thepresent invention (hereinafter to be also referred to as “thecomposition for depressive state of the present invention” in thepresent specification) contains one or more kinds of essential aminoacids other than leucine (i.e., one or more kinds selected from thegroup consisting of isoleucine, valine, threonine, lysine, methionine,histidine, phenylalanine and tryptophan), and not less than 35 mol % ofleucine relative to the total content of essential amino acids.

In the present specification, the “depressive state” refers to a statein which the mood is depressed and dislikes activity, due to whichthought, behavior, emotion, and happiness are influenced.

Specifically, it is a state having as a main complaint at least one of“apathy”, “feeling blue”, “feeling tired both physically and mentally”,“unable to get out of sorrow”, “unable to concentrate on thinking,unable to concentrate, or unable to make judgment”, “irritated or unableto stay calm”, “feeling miserable or caught by sense of inferiority”,“heavy head or heavy body”, “waking up feeling bad, or unable to wake upin the morning”, “having difficulty falling asleep, unable to sleep”,“unable to read books or newspapers, or unable to understand even afterreading”, “not wanting to meet people, wanting to stay home withoutgoing anywhere, feeling troublesome to move”, “feeling lonely, feelinganxiety, feeling alienated, or feeling strange”, “no appetite, or notfeeling food delicious”, “feeling painful, feeling despair, or wishingto die” and the like.

The cause of depressive state includes bereavement and separation fromclosest family member or pets, distress in human relations, job change,job transfer, promotion, personnel reshuffle, compulsory retirement,restructuring, business bankruptcy, failure in academic work or job,discouragement, romantic breakup, divorce, child independence, illness,overwork, accident, climacteric disorder, pregnancy, childbirth, moving,construction of new house, sudden change in living environment,affliction, internal stress from growing history and life history,mental or physical stress from age-related degradation of physical andmental functions and the like; physical disease such as brain disorder,chronic disease, endocrine disease and the like; side effects ofmedicaments such as interferon preparation, adrenal cortical steroiddrug (prednisone etc.), and antihypertensive agent (valsartan,amlodipine besylate, etc.), and the like.

The term “prevention of a depressive state” refers to suppression ofappearance of the depressive state described above, and “improvement ofa depressive state” refers to reduction of symptoms or level of theobserved depressive state.

In the present invention, “leucine” and “essential amino acid other thanleucine” used may be any of an L form, a D form and a DL form. An L formand a DL form are preferably used, and an L form is more preferablyused.

In the present invention, “leucine” and “essential amino acid other thanleucine” can be used not only in a free form but also a salt form. Theterm “leucine” and “essential amino acid other than leucine” in thepresent specification are concepts each encompassing even a salt. Thesalt form is not particularly limited as long as it is apharmacologically acceptable salt, and acid addition salt, salt withbase and the like can be mentioned.

Concrete examples include salts with inorganic bases, salts with organicbases, salts with inorganic acids, salts with organic acids, salts withamino acid and the like.

Examples of the salts with inorganic bases include salts with alkalimetals such as lithium, sodium, potassium and the like, salts withalkaline earth metals such as magnesium, calcium and the like, ammoniumsalt and the like.

Examples of the salts with organic bases include salts with alkanolaminesuch as monoethanolamine, diethanolamine, triethanolamine and the like,salts with heterocyclic amine such as morpholine, piperidine and thelike, and the like.

Examples of the salts with inorganic acids include salts with hydrohalicacid (hydrochloric acid, hydrobromic acid, hydroiodic acid etc.),sulfuric acid, nitric acid, phosphoric acid and the like.

Examples of the salts with organic acids include salts withmonocarboxylic acid such as formic acid, acetic acid, propanoic acid andthe like; salts with saturated dicarboxylic acid such as oxalic acid,malonic acid, malic acid, succinic acid and the like; salts withunsaturated dicarboxylic acid such as maleic acid, fumaric acid and thelike; salts with tricarboxylic acid such as citric acid and the like;salts with keto acid such as α-ketoglutaric acid and the like.

Examples of the salts with amino acid include salts with aliphatic aminoacid such as glycine, alanine and the like; salts with aromatic aminoacid such as tyrosine and the like; salts with basic amino acid such asarginine and the like; salts with acidic amino acid such as asparticacid, glutamic acid and the like; salts with amino acid forming lactamsuch as pyroglutamic acid and the like; and the like.

The above-mentioned salts may each be a hydrate (salt hydrate), andexamples of the hydrate include 1 hydrate to 6 hydrate and the like.

In the present invention, one kind each of “leucine” and “essentialamino acid other than leucine” in the above-mentioned free form or saltform may be used singly, or two or more kinds thereof may be used incombination.

For the object of the present invention, a free form, hydrochloride orthe like of each of “leucine” and “essential amino acid other thanleucine” is preferable.

In the present invention, the above-mentioned each amino acid in a freeform or salt form to be used may be extracted from animals, plants orthe like, which are naturally present, and purified, or obtained by achemical synthesis method, a fermentation method, an enzyme method or agene recombinant method and the like. Commercially available productsprovided by each company may also be utilized.

In the composition for dementia of the present invention, leucine iscontained at a high content of not less than 35 mol % relative to thetotal content of essential amino acids.

In the present specification, the content of each amino acid such asleucine in the composition for dementia of the present invention when itis contained in a salt form is shown by the content converted to that ofa free form.

From the aspect of the effect of preventing or improving dementia, thecontent of leucine is preferably 35 mol % to 66 mol %, more preferably35 mol % to 57 mol %, further preferably 35 mol % to 50 mol %, relativeto the total content of essential amino acids.

The content of isoleucine contained as essential amino acid other thanleucine is preferably 5 mol % to 15 mol % relative to the total contentof the essential amino acids.

The content of valine contained as essential amino acid other thanleucine is preferably 5 mol % to 15 mol % relative to the total contentof the essential amino acids.

The content of threonine contained as essential amino acid other thanleucine is preferably 7 mol % to 14 mol % relative to the total contentof the essential amino acids.

The content of lysine contained as essential amino acid other thanleucine is preferably 8 mol % to 16 mol % relative to the total contentof the essential amino acids.

The content of methionine contained as essential amino acid other thanleucine is preferably 2 mol % to 10 mol % relative to the total contentof the essential amino acids.

The content of histidine contained as essential amino acid other thanleucine is preferably 0.1 mol % to 3.5 mol % relative to the totalcontent of the essential amino acids.

The content of phenylalanine contained as essential amino acid otherthan leucine is preferably 2.5 mol % to 8 mol % relative to the totalcontent of the essential amino acids.

The content of tryptophan contained as essential amino acid other thanleucine is preferably 0.1 mol % to 2 mol % relative to the total contentof the essential amino acids.

From the aspect of the effect of preventing or improving dementia, thecomposition for dementia of the present invention more preferablycontains isoleucine, valine, threonine, lysine, methionine, histidine,phenylalanine and tryptophan at the above-mentioned contents asessential amino acids other than leucine.

In the composition for depressive state of the present invention,leucine is contained at a high content of not less than 35 mol %relative to the total content of essential amino acids.

In the present specification, the content of each amino acid such asleucine in the composition for depressive state of the present inventionwhen it is contained in a salt form is shown by the content converted tothat of a free form.

From the aspect of a preventive or improving effect on a depressivestate, the content of leucine is preferably 35 mol % to 66 mol %, morepreferably 35 mol % to 57 mol %, further preferably 35 mol % to 50 mol%, relative to the total content of essential amino acids.

The content of isoleucine contained as essential amino acid other thanleucine is preferably 5 mol % to 15 mol % relative to the total contentof the essential amino acids.

The content of valine contained as essential amino acid other thanleucine is preferably 5 mol % to 15 mol % relative to the total contentof the essential amino acids.

The content of threonine contained as essential amino acid other thanleucine is preferably 7 mol % to 14 mol % relative to the total contentof the essential amino acids.

The content of lysine contained as essential amino acid other thanleucine is preferably 8 mol % to 16 mol % relative to the total contentof the essential amino acids.

The content of methionine contained as essential amino acid other thanleucine is preferably 2 mol % to 10 mol % relative to the total contentof the essential amino acids.

The content of histidine contained as essential amino acid other thanleucine is preferably 0.1 mol % to 3.5 mol % relative to the totalcontent of the essential amino acids.

The content of phenylalanine contained as essential amino acid otherthan leucine is preferably 2.5 mol % to 8 mol % relative to the totalcontent of the essential amino acids.

The content of tryptophan contained as essential amino acid other thanleucine is preferably 0.1 mol % to 2 mol % relative to the total contentof the essential amino acids.

From the aspect of a preventive or improving effect on a depressivestate, the composition for depressive state of the present inventionmore preferably contains isoleucine, valine, threonine, lysine,methionine, histidine, phenylalanine, and tryptophan at theabove-mentioned contents as essential amino acids other than leucine.

The composition for dementia or composition for depressive state of thepresent invention may further contain other nutrition components such ascarbohydrate, lipid, protein, non-essential amino acid, vitamin, mineraland the like, in addition to the above-mentioned essential amino acids.

The composition for dementia or composition for depressive state of thepresent invention can be formulated into various forms such as liquidssuch as solution, suspension, emulsion and the like; semi-solid such asgel, cream and the like; solid such as powder, granule, tablet, capsuleand the like, and the like by adding other nutrition components andpharmaceutically acceptable additives to leucine and essential aminoacid other than leucine as necessary and according to a formulatingmeans well known in the field of preparations, for example, the methodsdescribed in the Japanese Pharmacopoeia XVII General Rules forpreparations [3] Monographs for Preparations, which is incorporatedherein by reference in its entirety, and the like.

The above-mentioned pharmaceutically acceptable additive can beappropriately selected according to the form of the composition fordementia or composition for depressive state of the present inventionand, for example, excipient, binder, disintegrant, lubricant, coatingagent, base, solvent, solubilizing agents, solubilizer, emulsifier,dispersing agent, suspending agent, stabilizer, thickener, soothingagent, isotonicity agent, pH adjuster, antioxidant, antiseptic,preservative, corrigent, sweetening agent, flavor, colorant and the likecan be mentioned.

To be specific, examples of the excipient include magnesium carbonate,saccharides (glucose, lactose, cornstarch, etc.), sugar alcohol(sorbitol, mannitol, etc.) and the like.

Examples of the binder include gelatin, pregelatinized starch, partlypregelatinized starch, cellulose and a derivative thereof (crystallinecellulose, hydroxypropylcellulose, etc.) and the like.

Examples of the disintegrant include crospovidone, povidone, crystallinecellulose and the like.

Examples of the lubricant include talc, magnesium stearate and the like.

Examples of the coating agent include methacrylic acid-methylmethacrylate copolymer, methacrylic acid-ethyl acrylate copolymer,methyl methacrylate-butyl methacrylate-dimethylaminoethyl methacrylatecopolymer, ethyl acrylate-methylmethacrylate-trimethylammonioethylmethacrylatechrolide copolymer and thelike.

Examples of the base include animal and plant fats and oils (olive oil,cacao butter, beef tallow, sesame oil, hydrogenated oil, castor oiletc.), wax (Carnauba wax, beeswax, etc.), polyethylene glycol and thelike.

Examples of the solvent include purified water, water for injection,monovalent alcohol (ethanol etc.), polyhydric alcohol (glycerol etc.)and the like.

Examples of the solubilizing agent include propylene glycol,medium-chain triglyceride and the like.

Examples of the solubilizer, emulsifier, dispersing agent and suspendingagent include surfactant and the like such as sorbitan fatty acid ester,glycerol fatty acid ester, polyoxyethylene sorbitan fatty acid ester(polysorbate 20, polysorbate 80, etc.), polyoxyethylene hydrogenatedcastor oil, sucrose fatty acid ester and the like.

Examples of the stabilizer include adipic acid, β-cyclodextrin,ethylenediamine, sodium edetate and the like.

Examples of the thickener include water-soluble polymer (sodiumpolyacrylate, carboxyvinyl polymer, etc.), polysaccharides (sodiumalginate, xanthan gum, tragacanth, etc.) and the like.

Examples of the soothing agent include ethyl aminobenzoate,chlorobutanol, propylene glycol, benzyl alcohol and the like.

Examples of the isotonicity agent include potassium chloride, sodiumchloride, sorbitol, saline and the like.

Examples of the pH adjuster include hydrochloric acid, sulfuric acid,acetic acid, citric acid, lactic acid, sodium hydroxide, potassiumhydroxide and the like.

Examples of the antioxidant include dibutylhydroxytoluene (BHT),butylhydroxyanisole (BHA), d1-α-tocopherol, erythorbic acid and thelike.

Examples of the antiseptic and preservative include paraben(methylparaben etc.), benzyl alcohol, sodium dehydroacetate, sorbic acidand the like.

Examples of the corrigent include ascorbic acid, erythritol, L-sodiumglutamate and the like.

Examples of the sweetening agent include aspartame, licorice extract,saccharin and the like.

Examples of the flavor include 1-menthol, d-camphor, vanillin and thelike.

Examples of the colorant include tar pigment (Food Color Red No. 2, FoodColor Blue No. 1, Food Color yellow No. 4, etc.), inorganic pigment (rediron oxide, yellow iron oxide, black iron oxide, etc.), natural dye(turmeric extract, β-carotene, sodium copper-chlorophyllin, etc.) andthe like.

In the present invention, one or more kinds of the above-mentionedadditive can be used.

The daily ingestion amount or dose of the composition for dementia ofthe present invention is appropriately determined according to the sex,age of the subject to be applied to (hereinafter to be also referred toas the “application subject” in the present specification), symptom orlevel of dementia observed in the application subject, the form of thecomposition for dementia of the present invention, administration methodand the like. When the application subject is a human adult, it isgenerally 0.5 g to 22 g, preferably 1 g to 20 g, more preferably 3 g to16 g, as the total amount of leucine and essential amino acid other thanleucine (the total amount converted to the amount of free form).

The above-mentioned amount can be ingested or administered at once or inseveral portions (e.g., 2 to 4 portions) per day.

In addition, the ingestion or dosing period of the composition fordementia of the present invention is also appropriately determinedaccording to the condition and symptoms of the application subject, andthe like. Considering that dementia develops along with aging, variousdiseases, lesions in the brain, and the like and progresses chronically,continuous ingestion or administration for a long period of time ispreferable to prevent or improve dementia.

The daily ingestion amount or dose of the composition for depressivestate of the present invention is appropriately determined according tothe sex, age of the application subject, symptom or level of depressivestate observed in the application subject, the form of the compositionfor depressive state of the present invention, administration method andthe like. When the application subject is a human adult, it is generally0.5 g to 22 g, preferably 1 g to 20 g, more preferably 3 g to 16 g, asthe total amount of leucine and essential amino acid other than leucine(the total amount converted to the amount of free form).

The above-mentioned amount can be ingested or administered at once or inseveral portions (e.g., 2 to 3 portions) per day.

In addition, the ingestion or dosing period of the composition fordepressive state of the present invention is also appropriatelydetermined according to the condition and symptoms of the depressivestate of the application subject, and the like. Considering that adepressive state is often caused by stress that is routinely applied, itis preferable to use the composition of the present invention forcontinuous ingestion or administration for a long period of time inorder to prevent or improve a depressive state.

The composition for dementia or composition for depressive state of thepresent invention can be formulated as a unit package form. In thepresent specification, the “unit package foam” means a form of one ormore units with a particular amount (e.g., ingestion amount or dose perone time etc.) as one unit is/are filled in one container or packed in apackage. For example, a unit package form with ingestion amount or doseper one time as one unit is referred to as “unit package form foringestion amount or dose per one time”. A container or package used forthe unit package form can be appropriately selected according to theform and the like of the composition for dementia or composition fordepressive state of the present invention. For example, paper containeror bag, plastic container or bag, pouch, aluminum can, steel can, glassbottle, pet bottle, PTP (press through pack) package sheet and the likecan be mentioned.

The application subject of the composition for dementia or compositionfor depressive state of the present invention includes, for example,mammals (e.g., human, monkey, mouse, rat, guinea pig, hamster, rabbit,cat, dog, bovine, horse, donkey, swine, sheep, etc.), birds (e.g., duck,chicken, goose, turkey, etc.) and the like.

When the composition for dementia or composition for depressive state ofthe present invention is applied to an application subject animal(hereinafter to be also simply referred to as “subject animal”) otherthan human, the ingestion amount or dose of the composition for dementiaor composition for depressive state of the present invention can beappropriately set according to the kind, sex, body weight and the likeof the subject animal.

Of the symptoms seen as core symptoms of dementia, the composition fordementia of the present invention more effectively prevents or improvesmemory disorders and is more effective in suppressing or improving adecline of cognitive function. In addition, it is particularly effectivefor preventing or improving Alzheimer-type dementia in which the contentof acetylcholine, a neurotransmitter in the brain, decreases.

Furthermore, since the composition for dementia of the present inventionis contained in foods and contains amino acids with abundant foodexperience as active ingredients, it is highly safe, suitable forcontinuous ingestion, and thus useful for preventing or improvingdementia.

Therefore, the composition for dementia of the present invention ispreferably ingested by or administered to patients showing symptoms ofdementia, patients with a risk of developing dementia, and elderlypeople and middle- or late middle-aged persons who require prevention ofdementia.

The composition for dementia of the present invention may beparticularly preferably ingested or administered by patients showingsymptoms of Alzheimer-type dementia, patients who may develop theaforementioned dementia, elderly people and middle- or late middle-agedpersons having a high onset risk of Alzheimer-type dementia, and thelike.

The composition for depressive state of the present invention iseffective for preventing or improving a depressive state caused byvarious factors, and particularly affords a good preventive or improvingeffect on a depressive state caused by mental or physical stress.

In addition, since the composition for depressive state of the presentinvention is contained in foods and contains amino acids with abundantfood experience as active ingredients, it is highly safe, suitable forcontinuous ingestion or administration, and thus useful for preventingor improving a depressive state caused by stress applied routinely.

Therefore, the composition for depressive state of the present inventionmay be preferably ingested or administered by those showing a depressivestate, as well as those with high possibility of developing a depressivestate such as elderly people suffering from age-related decline inphysical function or mental function, and middle- or late middle-agedpersons who often suffer from various stresses in workplace, home, andthe like.

The composition for dementia of the present invention can be provided asa pharmaceutical product (hereinafter to be also referred to as “thepharmaceutical product for dementia of the present invention” in thepresent specification) directly or by further adding the above-mentionedpharmaceutically acceptable additives.

The pharmaceutical product for dementia of the present invention canhave a dosage form of oral preparation such as tablet, coating tablet,chewable tablet, pill, (micro)capsule, granule, fine granule, powder,elixir, lemonade, syrup, suspension, emulsion, oral jelly and the like,injection such as solution, suspension, emulsion and the like, solidinjection to be used by dissolving or suspending when in use, injectablepreparation such as transfusion, sustainable injection and the like,tubal liquid, and the like.

The pharmaceutical product for dementia of the present invention maycontain an anti-dementia drug as long as the characteristics of thepresent invention are not impaired.

Examples of the anti-dementia drug include acetylcholinesteraseinhibitors such as donepezil hydrochloride, galanthamine, rivastigmineand the like; and NMDA receptor antagonists such as memantine and thelike, and these can be used according to general dosage.

The pharmaceutical product for dementia of the present invention may bepreferably administered to patients with dementia, patients who maydevelop dementia, elderly people and middle- or late middle-aged personshaving a high onset risk of dementia, and the like.

The pharmaceutical product for dementia of the present invention isadministered to the above-mentioned application subject such that thetotal amount per day of leucine and essential amino acid other thanleucine is the above-mentioned dose per day.

The composition for depressive state of the present invention can beprovided as a pharmaceutical product (hereinafter to be also referred toas “the pharmaceutical product for depressive state of the presentinvention” in the present specification) directly or by further addingthe above-mentioned pharmaceutically acceptable additives.

The pharmaceutical product for depressive state of the present inventioncan have a dosage form of oral preparation such as tablet, coatingtablet, chewable tablet, pill, (micro)capsule, granule, fine granule,powder, elixir, lemonade, syrup, suspension, emulsion, oral jelly andthe like, injection such as solution, suspension, emulsion and the like,solid injection to be used by dissolving or suspending when in use,injectable preparation such as transfusion, sustainable injection andthe like, tubal liquid, and the like.

The pharmaceutical product for depressive state of the present inventionmay contain an antidepressant as long as the characteristics of thepresent invention are not impaired.

Examples of the antidepressant include tricyclic antidepressants such asimipramine hydrochloride, clomipramine hydrochloride, trimipraminemaleate and the like; tetracyclic antidepressants such as maprotilinehydrochloride, mianserin hydrochloride, setiptiline maleate and thelike; selective serotonin reuptake inhibitors such as fluvoxaminemaleate, paroxetine hydrochloride hydrate and the like; selectiveserotonin-noradrenaline reuptake inhibitors such as milnacipranhydrochloride and the like. These can be used according to a generaldosage.

The pharmaceutical product for depressive state of the present inventionmay be preferably administered to those showing a depressive state andthose with high possibility of developing a depressive state by beingexposed to various stresses.

The pharmaceutical product for depressive state of the present inventionis administered to the above-mentioned application subject such that thetotal amount per day of leucine and essential amino acid other thanleucine is the above-mentioned dose per day.

Furthermore, the composition for dementia of the present invention canbe ingested by adding to various foods. The food to which thecomposition of the present invention is added is not particularlylimited, and may be any as long as it is a food in the form generallyserved for meals or dessert.

For example, the composition for dementia of the present invention isadded to drinks such as beverage water and the like, and a suitableflavor is added when desired, whereby a drink can be provided.

More specifically, the composition for dementia of the present inventioncan be added, for example, to beverage water such as fruit juice drinks,sport drinks and the like; dairy products such as milk, yogurt and thelike; confectionery such as jelly, chocolate, candy and the like, andthe like.

The composition for dementia of the present invention is preferablyadded to the above-mentioned various foods in amounts to be ingested perday such that the total amount of leucine and essential amino acid otherthan leucine is the above-mentioned dose per day.

The composition for dementia of the present invention can be provided asa food (hereinafter to be also referred to as “the food for dementia ofthe present invention” in the present specification) directly or byadding general food additives as necessary and according to a generalfood production technique.

The food for dementia of the present invention can be prepared asvarious forms such as liquid, suspension, emulsified liquid, gel, cream,powder, granule, sheet, capsule, tablet and the like.

Furthermore, the food for dementia of the present invention can beprepared as various food forms such as beverage water (fruit juicedrinks, sport drinks, coffee drinks, tea drinks, etc.), dairy product(lactic fermenting beverage, fermented milk, butter, cheese, yogurt,processed milk, defatted milk, etc.), meat product (ham, sausage,hamburger, etc.), fish meat processed seafood paste product (fish cake,tube-shaped fish sausage, deep-fried ball of fish paste, etc.), eggproduct (rolled Japanese-style omelette, steamed egg custard, etc.),confectionery (cookie, jelly, chewing gum, candy, snack food, frozendessert, etc.), bread, noodles, pickle, dried fish, food boiled in soysauce, soup, seasoning and the like by adding the composition fordementia of the present invention to various food starting materials andadding general food additives as necessary. It may also be a bottledfood, canned food or retort pouch food.

As the above-mentioned food additive, manufacturing agent (brine,binding agent, etc.), thickening stabilizer (xanthan gum, sodiumcarboxymethylcellulose, etc.), gelling agent (gelatin, agar,carrageenan, etc.), gum base (vinyl acetate resin, jelutong, chicle,etc.), emulsifier (glycerol fatty acid ester, sucrose fatty acid ester,saponin, lecithin, etc.), preservative (benzoic acid, sodium benzoate,sorbic acid, potassium sorbate, ϵ-polylysine, etc.), antioxidant(ascorbic acid, erythorbic acid, catechin, etc.), glazing agent(shellac, paraffin wax, beeswax, etc.), fungicide (thiabendazole,fludioxonil, etc.), leavening agent (sodium hydrogen carbonate, gluconoδ-lactone, alum, etc.), sweetener (aspartame, acesulfame potassium,licorice extract, etc.), bittering agent (caffeine, naringin, worm woodextract, etc.), acidulant (citric acid, tartaric acid, lactic acid,etc.), seasoning (sodium L-glutamate, disodium 5′-inosinate, etc.),colorant (annatto dye, turmeric dye, gardenia dye, etc.), flavor(synthetic flavor such as ethyl acetoacetate, anisealdehyde and thelike, natural flavor such as orange, lavender and the like) and the likecan be mentioned.

In the present invention, one or more kinds of the above-mentioned foodadditives can be used.

The food for dementia of the present invention may be preferablyingested by those requiring improvement in the symptoms of dementia,those with a risk of developing dementia, elderly people and middle- orlate middle-aged persons who have a high risk of developing dementia andthe like.

In addition, the food for dementia of the present invention can bewidely ingested by subjects besides dementia patients and elderly peopleand middle- or late middle-aged persons who have a high risk ofdeveloping dementia for the purpose of preventing dementia.

Therefore, the food for dementia of the present invention can also beprovided as food with health claims such as food for specified healthuses, food with nutrient function claims, indicated functional food andthe like, special purpose foods such as food for sick people, food forthe elderly and the like, health supplement, dietary supplement and thelike for preventing or improving dementia.

The food for dementia of the present invention is preferably ingested bythe above-mentioned application subject such that the total amount ofleucine and essential amino acid other than leucine per day is theabove-mentioned ingestion amount per day.

Furthermore, the composition for depressive state of the presentinvention can be ingested by adding to various foods. The food to whichthe composition for depressive state of the present invention is addedis not particularly limited, and may be any as long as it is a food inthe form generally served for meals or dessert.

For example, the composition for depressive state of the presentinvention is added to drinks such as beverage water and the like, and asuitable flavor is added when desired, whereby a drink can be provided.

More specifically, the composition for depressive state of the presentinvention can be added, for example, to beverage water such as fruitjuice drinks, sport drinks and the like; dairy products such as milk,yogurt and the like; confectionery such as jelly, chocolate, candy andthe like, and the like.

The composition for depressive state of the present invention ispreferably added to the above-mentioned various foods in amounts to beingested per day such that the total amount of leucine and essentialamino acid other than leucine is the above-mentioned dose per day.

The composition for depressive state of the present invention can beprovided as a food (hereinafter to be also referred to as “the food fordepressive state of the present invention” in the present specification)directly or by adding the above-mentioned general food additives asnecessary and according to a general food production technique.

The food for depressive state of the present invention can be preparedas various forms such as liquid, suspension, emulsified liquid, gel,cream, powder, granule, sheet, capsule, tablet and the like.

Furthermore, the food for depressive state of the present invention canbe prepared as various food forms such as beverage water (fruit juicedrinks, sport drinks, coffee drinks, tea drinks, etc.), dairy product(lactic fermenting beverage, fermented milk, butter, cheese, yogurt,processed milk, defatted milk, etc.), meat product (ham, sausage,hamburger, etc.), fish meat processed seafood paste product (fish cake,tube-shaped fish sausage, deep-fried ball of fish paste, etc.), eggproduct (rolled Japanese-style omelette, steamed egg custard, etc.),confectionery (cookie, jelly, chewing gum, candy, snack food, frozendessert, etc.), bread, noodles, pickle, dried fish, food boiled in soysauce, soup, seasoning and the like by adding the composition fordepressive state of the present invention to various food startingmaterials and adding the above-mentioned general food additives asnecessary. It may also be a bottled food, canned food or retort pouchfood.

The food for depressive state of the present invention may be preferablyingested by those requiring improvement of a depressive state. Inaddition, it can be widely ingested for the purpose of preventing adepressive state by those who may develop a depressive state by beingexposed to various stresses.

Therefore, the food for depressive state of the present invention canalso be provided as food with health claims such as food for specifiedhealth uses, food with nutrient function claims, indicated functionalfood and the like, special purpose foods such as food for sick people,food for the elderly and the like, health supplement, dietary supplementand the like for preventing or improving a depressive state.

The food for depressive state of the present invention is preferablyingested by the above-mentioned application subject such that the totalamount of leucine and essential amino acid other than leucine per day isthe above-mentioned ingestion amount per day.

Furthermore, the present invention also provides a method for preventingor improving dementia in a subject animal in need of prevention orimprovement of dementia (hereinafter to be also referred to as the“preventive/improving method of dementia of the present invention” inthe present specification).

The preventive/improving method of dementia of the present inventionincludes ingestion or administration to a subject animal in need ofprevention or improvement of symptoms of dementia of leucine andessential amino acid other than leucine in amounts effective forpreventing or improving the symptoms of dementia of the subject animal.

Of the symptoms seen as core symptoms of dementia, thepreventive/improving method of dementia of the present invention is moreeffective for preventing or improving memory disorders and decline ofcognitive function and particularly effective for preventing orimproving Alzheimer-type dementia.

In the case of human, the preventive/improving method of dementia of thepresent invention is preferably applied to dementia patients requiringimprovement of memory disorder and a decline of cognitive function,patients with a risk of developing dementia, and elderly people andmiddle- or late middle-aged persons who have a high risk of developingdementia and the like.

While the effective amount of leucine and essential amino acid otherthan leucine in the method for the prevention/improvement of dementia ofthe present invention is determined according to the kind, age, sex,level of symptoms of dementia, condition and the like of the subjectanimal, an amount similar to the above-mentioned ingestion amount ordose of the composition for dementia of the present invention for ahuman or a subject animal other than human can be ingested oradministered at the frequency and period mentioned above.

Furthermore, the present invention also provides a method for preventingor improving a depressive state in a subject animal in need ofprevention or improvement of a depressive state (hereinafter to be alsoreferred to as the “preventive/improving method of depressive state ofthe present invention” in the present specification).

The preventive/improving method of depressive state of the presentinvention includes ingestion or administration to a subject animal inneed of prevention or improvement of a depressive state of leucine andessential amino acid other than leucine in amounts effective forpreventing or improving a depressive state of the subject animal.

The preventive/improving method of depressive state of the presentinvention is effective for preventing or improving a depressive state,and particularly effective for preventing or improving a depressivestate caused by stress.

In the case of human, the preventive/improving method of depressivestate of the present invention may be preferably applied to thoseshowing a depressive state and requiring improvement thereof, or thosewho may develop a depressive state by being exposed to various stresses.

While the effective amount of leucine and essential amino acid otherthan leucine in the method for the prevention/improvement of depressivestate of the present invention is determined according to the kind, age,sex, symptoms and the level of depressive state and the like of thesubject animal, an amount similar to the above-mentioned ingestionamount or dose of the composition for depressive state of the presentinvention for a human or a subject animal other than human can beingested or administered at the frequency and period mentioned above.

The subject animal in the present invention includes mammal (e.g.,human, monkey, mouse, rat, guinea pig, hamster, rabbit, cat, dog,bovine, horse, donkey, swine, sheep, etc.), birds (e.g., duck, chicken,goose, turkey, etc.) and the like.

The ingestion or administration method of leucine and essential aminoacid other than leucine in the present invention includes oraladministration, enteral tube administration, administration by infusionand the like. Oral administration is preferable since convenientingestion is possible without the need to perform under the guidance andsupervision of a doctor at a medical institution.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention and are not intended to be limitingthereof.

EXAMPLES Example 1. Composition for Preventing or Improving Dementia

To afford the composition shown in Table 1, given amounts of respectivecomponents were weighed and mixed to prepare the composition forpreventing or improving dementia of Example 1 (hereinafter sometimes tobe referred to as “the composition of Example 1”).

TABLE 1 molar composition ratio (%) relative to total content ofcomponent essential amino acids L-leucine 42.1 L-isoleucine 11.2L-valine 13.0 L-threonine 10.8 L-lysine hydrochloride 12.6 L-methionine3.1 L-histidine hydrochloride 1-hydrate 1.1 L-phenylalanine 5.6L-tryptophan 0.5

Experimental Example 1. Study of Action of Composition of Example 1 onCognitive Function

Using SAMP8 which is a senescence accelerated mouse model and learningand memory disorder mouse model, and SAMR1 which is a control mousetherefor (both 10-week-old, male) (purchased from CHARLES RIVERLABORATORIES JAPAN, INC.), an action of the composition of Example 1 oncognitive function was studied.

The respective mice of SAMP8 and SAMR1 were divided into 3 groups shownin Table 2 (n=16/group), reared from the day of arrival to the day ofautopsy while allowing them to freely eat a feed containing 16% byweight of casein, and the composition (AL40) of Example 1 or deionizedwater (vehicle) was forcibly administered orally at 1 g/kg body weighttwice per day (morning and evening) continuously (except Saturday andSunday).

TABLE 2 group feed n number SAMR1 feed containing 16 wt % casein + 16deionized water SAMP8- feed containing 16 wt % casein + 16 vehicledeionized water SAMP8- feed containing 16 wt % casein + 16 AL40composition of Example 1

(1) Study of Action on Spatial Working Memory (Short Term Memory)

The mice of each group shown in Table 2 were subjected to a Y maze testas follows at 10, 13, 15, 17, 19, 21, and 23 weeks of age (oraladministration of the composition of Example 1 or deionized water wasstopped in the morning of the day of Y m maze test).

Using a Y-shaped maze device, the mouse was placed on one of the armsthereof and allowed to move freely for 8 min, and the number of timesthe mouse entered the arm was recorded. At that time, the mouse wastaken to have “entered” when the base of the tail entered the arm.

It is considered that the Y maze test can evaluate the spontaneousbehavior and spatial working memory (short term memory) of mouse.

The spontaneous behavior of the mouse can be evaluated by the totalnumber of times the mouse entered the arm. Using a group in whichdeionized water was orally administered to SAMP8 (SAMP8-vehicle) and agroup in which the composition of Example 1 was orally administered toSAMP8 (SAMP8-AL40), changes in the total number of times the mouseentered the arm were compared based on the age and shown in FIG. 1 asmean±standard error of mean of 16 mice. For the measurement results ofthe total number of entries of the mouse, two-factor analysis ofvariance and multiple comparison test of Bonferroni were performed.

As an index of spatial working memory (short term memory), a value wasobtained by dividing the number of three successive entries intodifferent arms by the number obtained by subtracting 1 from the totalnumber of arm entries, and then multiplying same by 100 (alternationbehavior value). The mean±standard error of mean of 16 mice of the groupin which deionized water was orally administered to SAMP8 at each weekof age (SAMP8-vehicle), and the group in which the composition ofExample 1 was orally administered to SAMP8 (SAMP8-AL40) were comparedand shown in FIG. 2. As for the alternation behavior value, Student'st-test was performed.

As shown in FIG. 1, a significant difference was not observed in the armentry number as an index of spontaneous behavior between the group inwhich deionized water was orally administered to SAMP8 (SAMP8-vehicle)and the group in which the composition of Example 1 was orallyadministered to SAMP8 (SAMP8-AL40) or according to the age in weeks.

On the other hand, as shown in FIG. 2, in the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)at 17-week-old, 19-week-old, 21-week-old and 23-week-old, thealternation behavior value increased significantly (P<0.05 for 17, 19,21 weeks of age, P<0.01 for 23 weeks of age), thus suggesting that thespatial working memory (short term memory) is improved by oraladministration of the composition of Example 1 as compared to the groupin which the group in which deionized water was orally administered(SAMP8-vehicle).

(2) Evaluation of Effect on Short-Term Memory and Long-Term Memory

The mice of each group shown in Table 2 were subjected at 23 weeks ofage to passive avoidance test as follows (oral administration of thecomposition of Example 1 or deionized water was stopped in the morningof the day of passive avoidance test).

(i) Using an apparatus composed of a light-dark compartment with anelectric stimulation device in the dark compartment, a mouse was placedin the light compartment, and the time (latency) before entering thedark compartment was measured for maximum 120 seconds. When the mouseentered the dark compartment, the door was closed simultaneously withthe entry, and an electric stimulation (2 mA, 1 sec) was applied. Theentry into the dark compartment was defined to be the time point whenthe base of the tail entered the dark compartment.

(ii) The trial of (i) was repeated 5 times at maximum until the mouseremained in the light compartment for 120 seconds.

(iii) Three days later, the mouse was placed in the light compartment,and the time when the mouse stayed in the light compartment (retentiontime) was measured for maximum 300 seconds.

In the passive avoidance test, from the test performed on the first day,the time required for the entry into a dark compartment (transferlatency time) and the number of trials required for staying in a lightcompartment for 120 seconds (trials to criterion) in each trial can beevaluated as short term memory. Furthermore, long-term memory can beevaluated from the time of stay in the light compartment 3 days later(retention time).

For the mice in each group, the time required for the entry into a darkcompartment in the first trial (transfer latency time) and the number oftrials required for staying in a light compartment for 120 seconds(trials to criterion) are shown each as mean±standard error of mean of16 mice in FIG. 3.

Furthermore, the number of mice that stayed in the light compartment for120 seconds in the second trial, that is, the ratio of the number ofmice that memorized that the dark compartment is scary by one electricstimulation (achievement by 1st ES) is shown together in FIG. 3. Thenumerical values in the Figure show the number of mice in each groupthat stayed in the light compartment for 120 seconds in the secondtrial.

The time of stay in the light compartment 3 days later (retention time)is shown in FIG. 4 as mean±standard error of mean of 16 mice. Thenumerical values in the Figure show the number of mice in each groupthat stayed in the light compartment for 300 seconds.

As for the time required for the entry into a dark compartment in thefirst trial (transfer latency time) and the number of trials requiredfor staying in a light compartment for 120 seconds (trials to criterion)and the time of stay in the light compartment 3 days later (retentiontime), Dunnett's multiple comparison test was performed.

As shown in FIG. 3, as compared to the group in which deionized waterwas orally administered to SAMR1 (SAMR1), the time required for theentry into a dark compartment (transfer latency time) in the first trialwas found to be significantly (P<0.05) shorter in other two groups.

In addition, the number of trials required for staying in a lightcompartment for 120 seconds (trials to criterion) was one in the groupin which deionized water was orally administered to SAMR1 (SAMR1), andmore than one and less than two both in the group in which deionizedwater was orally administered to SAMP8 (SAMP8-vehicle) and the group inwhich the composition of Example 1 was orally administered to SAMP8(SAMP8-AL40). However, the aforementioned number of trials significantly(P<0.005) increased in the group in which deionized water was orallyadministered to SAMP8 (SAMP8-vehicle) as compared to the group in whichdeionized water was orally administered to SAMR1 (SAMR1), whereas theaforementioned number of trials decreased in the group in which thecomposition of Example 1 was orally administered to SAMP8 (SAMP8-AL40)to the extent that a significant difference from the group in whichdeionized water was orally administered to SAMR1 (SAMR1) was not found.

The ratio of the number of mice that memorized that the dark compartmentis scary by one electric stimulation (achievement by 1st ES) clearlyincreased in the group in which the composition of Example 1 was orallyadministered to SAMP8 (SAMP8-AL40) as compared to the group in whichdeionized water was orally administered to SAMP8 (SAMP8-vehicle).

Furthermore, as shown in FIG. 4, the time of stay in the lightcompartment 3 days later (retention time) also significantly (P<0.01)decreased in the group in which deionized water was orally administeredto SAMP8 (SAMP8-vehicle) as compared to the group in which deionizedwater was orally administered to SAMR1 (SAMR1). However, in the group inwhich the composition of Example 1 was orally administered to SAMP8(SAMP8-AL40), the time increased to the same level as in the group inwhich deionized water was orally administered to SAMR1 (SAMR1).

From the results of the above-mentioned passive avoidance test, it wassuggested that the composition of Example 1 of the present invention mayimprove both the short term memory and long term memory.

(3) Evaluation of Effect on Hippocampal Neruron

The mice of each group shown in Table 2 were autopsied at 23 weeks ofage after completion of the above-mentioned respective tests, andhippocampal section was produced and Klüver-Barrera stained.

Under a microscope (“DFC350FX”, manufactured by Leica, magnification: 20times), digital filming of the CA1 region was performed and the numberof neurons per a fixed pixel was measured for the image by using ananalysis software (“image-J”, an open resource produced by NIH (NationalInstitutes of Health)). Then, the number of pixels was converted tosquare millimeters, and the number of neurons per unit area wascalculated. The calculated number of neurons is shown as mean±standarderror of mean of 16 mice and Dunnett's multiple comparison test wasperformed.

The Klüver-Barrera staining image under the microscope is shown in FIG.5 and the measurement results of the number of neurons are shown in FIG.6.

As shown in FIG. 5 and FIG. 6, a significant (P<0.01) decrease inneurons in hippocampal CA1 region was found in the group in whichdeionized water was orally administered to SAMP8 (SAMP8-vehicle) ascompared to the group in which deionized water was orally administeredto SAMR1 (SAMR1). In contrast, in the group in which the composition ofExample 1 was orally administered to SAMP8 (SAMP8-AL40), a decrease inthe neurons was not found and the presence of neurons at the same levelas in the group in which deionized water was orally administered toSAMR1 (SAMR1) was confirmed.

Therefore, the composition of Example 1 of the present inventionsuppressed the loss of neuron in hippocampus, and the possibility ofsuppressing memory disorders and a decline of cognitive function wassuggested.

(4) Evaluation of Effect on Acetylcholine Content of Prefrontal Cortex

The mice of each group shown in Table 2 were autopsied at 23 weeks ofage after completion of the above-mentioned respective tests, and ahomogenate of prefrontal cortex (PFC) was prepared. Using ELISA(Enzyme-Linked ImmunoSorbent Assay) kit, acetylcholine content wasquantified, and the acetylcholine content per 1 mg protein in thehomogenate of prefrontal cortex (PFC) is shown in FIG. 7 (mean±standarderror of mean of 16 mice). The quantification results were applied toHolm-Sidak's multiple comparison test.

As shown in FIG. 7, in the group in which the composition of Example 1was orally administered to SAMP8 (SAMP8-AL40), it was found that theacetylcholine content in PFC significantly (P<0.005) increased ascompared to the group in which deionized water was orally administeredto SAMR1 (SAMR1). In addition, a tendency toward increase (P=0.0615) wasalso shown as compared to the group in which deionized water was orallyadministered to SAMP8 (SAMP8-vehicle).

Acetylcholine is a neurotransmitter known to decrease in the brain ofpatients with Alzheimer-type dementia.

Therefore, the above-mentioned evaluation results suggest that thecomposition of Example 1 of the present invention may improveAlzheimer-type dementia.

Example 2. Composition for Preventing or Improving Depressive State

To afford the composition shown in Table 3, given amounts of respectivecomponents were weighed and mixed to prepare the composition forpreventing or improving depressive state of Example 2 (hereinaftersometimes to be referred to as “the composition of Example 2”).

TABLE 3 ratio (mol %) of molar composition relative to total content ofcomponent essential amino acids L-leucine 42.1 L-isoleucine 11.2L-valine 13.0 L-threonine 10.8 L-lysine hydrochloride 12.6 L-methionine3.1 L-histidine 1.1 L-phenylalanine 5.6 L-tryptophan 0.5

Experimental Example 2. Study of Effect of Composition of Example 2 onDepressive State

Using BL6J mouse (10-week-old, male) (purchased from CHARLES RIVERLABORATORIES JAPAN, INC.), the effect of the composition of Example 2 ona depressive state was studied.

The BL6J mice were divided into 3 groups shown in Table 4 (n=12/group),KN209 breeding room was set as a dark compartment from 7 to 19 and alight compartment from 19 to 7 and one mouse was placed and reared inone cage and reared from the day of arrival to the day of autopsy whileallowing them to freely eat a feed containing 16% by weight of casein,and the composition (AL40) of Example 2 or deionized water (vehicle) wasforcibly administered orally at 1 g/kg body weight twice per day(morning and evening) continuously (except Saturday and Sunday). Duringthe rearing period, various stresses (CUS: chronic unpredictable stress)were applied according to the stress load menu shown in FIG. 8 to thegroup in which deionized water was orally administered to stressed mouse(CUS-vehicle), and the group in which the composition of Example 2 wasorally administered to stressed mouse (CUS-AL40).

TABLE 4 group presence or absence of stress load, feed n number CUS-with stress load, 16 wt % casein- 12 vehicle containing feed + deionizedwater CUS-AL40 with stress load, 16 wt % casein- 12 containing feed +composition of Example 1 Free- without stress load, 16 wt % casein- 12vehicle containing feed + deionized water

The body weight of each mouse was measured on days 6, 13, 20, 27, and 31of rearing, and mean±standard error of mean of each group is shown inFIG. 9. In addition, increase in the body weight of mice in each group(difference in body weight between day 31 of rearing from that on theday of start of rearing) is shown in FIG. 10.

As shown in FIG. 9 and FIG. 10, an increase in the body weight wastended to be suppressed in the group in which deionized water was orallyadministered to stress-loaded mice (CUS-vehicle) and the group in whichthe composition of Example 2 was orally administered to stress-loadedmouse (CUS-AL40), as compared to the group in which deionized water wasorally administered to mouse without stress (Free-vehicle).

On day 30 of rearing, a forced swimming test (1 L cylinder, roomtemperature, 6 minutes) was performed for the mice of each group.

In the forced swimming test, a mouse placed in a water tank firststruggles, swims around, but thereafter stops moving while floating inwater with only the tip of the nose sticking out from the water surface.The time during which the mouse does not move (immobility time) is takenas an index of a depressive state.

The immobility time of the mice of each group was measured and theresults are shown in FIG. 11. The measurement results were applied toHolm-Sidak's multiple comparison test.

As shown in FIG. 11, immobility time significantly (P<0.0001) increasedin the group in which deionized water was orally administered tostress-loaded mice (CUS-vehicle) and the group in which the compositionof Example 2 was orally administered to stress-loaded mouse (CUS-AL40),as compared to the group in which deionized water was orallyadministered to mouse without stress (Free-vehicle). However, it wasfound that the immobility time was significantly (P<0.05) short in thegroup in which the composition of Example 2 was orally administered tostress-loaded mouse (CUS-AL40), as compared to the group in whichdeionized water was orally administered to stress-loaded mice(CUS-vehicle).

The above-mentioned evaluation results suggest that the composition ofExample 2 of the present invention may improve the depressive statecaused by stress.

INDUSTRIAL APPLICABILITY

As described in detail above, a composition for preventing or improvingdementia can be provided according to the present invention.

The composition for preventing or improving dementia of the presentinvention effectively prevents or improves memory disorders, is alsoeffective for the suppression or improvement of a decline of cognitivefunction, and particularly effective for preventing or improvingAlzheimer-type dementia.

Furthermore, the composition for preventing or improving dementia of thepresent invention is highly safe and suitable for continuous ingestionor administration.

According to the present invention, a composition for preventing orimproving a depressive state, which can favorably prevent or improve thedepressive state can be provided.

The composition for preventing or improving a depressive state of thepresent invention is particularly effective for m preventing orimproving a depressive state caused by stress.

Furthermore, the composition for preventing or improving a depressivestate of the present invention has high safety and is suitable forcontinuous ingestion or administration.

Where a numerical limit or range is stated herein, the endpoints areincluded. Also, all values and subranges within a numerical limit orrange are specifically included as if explicitly written out.

As used herein the words “a” and “an” and the like carry the meaning of“one or more.”

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that, within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

All patents and other references mentioned above are incorporated infull herein by this reference, the same as if set forth at length.

1. A composition for preventing or improving dementia, comprising one ormore kinds of essential amino acids other than leucine and not less than35 mol % of leucine, relative to the total content of essential aminoacids.
 2. The composition according to claim 1, wherein the content ofleucine is 35 mol % to 66 mol %, relative to the total content ofessential amino acids.
 3. The composition according to claim 1, whereinone or more kinds of essential amino acids other than leucine areisoleucine, valine, threonine, lysine, methionine, histidine,phenylalanine, and tryptophan.
 4. The composition according to claim 3,wherein a molar composition ratio of the content of each amino acid,relative to the total content of essential amino acids, falls within thefollowing numerical values: leucine: 35 mol % to 66 mol % isoleucine: 5mol % to 15 mol % valine: 5 mol % to 15 mol % threonine: 7 mol % to 14mol % lysine: 8 mol % to 16 mol % methionine: 2 mol % to 10 mol %histidine: 0.1 mol % to 3.5 mol % phenylalanine: 2.5 mol % to 8 mol %tryptophan: 0.1 mol % to 2 mol %.
 5. The composition according to claim1, wherein the composition is a pharmaceutical product.
 6. Thecomposition according to claim 1, wherein the composition is a food. 7.A composition for preventing or improving a depressive state, comprisingone or more kinds of essential amino acids other than leucine and notless than 35 mol % of leucine, relative to the total content ofessential amino acids.
 8. The composition according to claim 7, whereinthe content of leucine is 35 mol % to 66 mol %, relative to the totalcontent of the essential amino acids.
 9. The composition according toclaim 7, wherein one or more kinds of essential amino acid other thanleucine includes isoleucine, valine, threonine, lysine, methionine,histidine, phenylalanine, and tryptophan.
 10. The composition accordingto claim 9, wherein a molar composition ratio of each amino acid,relative to the total content of the essential amino acids, is withinthe following numerical range: leucine: 35 mol % to 66 mol % isoleucine:5 mol % to 15 mol % valine: 5 mol % to 15 mol % threonine: 7 mol % to 14mol % lysine: 8 mol % to 16 mol % methionine: 2 mol % to 10 mol %histidine: 0.1 mol % to 3.5 mol % phenylalanine: 2.5 mol % to 8 mol %tryptophan: 0.1 mol % to 2 mol %.
 11. The composition according to claim7, wherein the composition is a pharmaceutical product.
 12. Thecomposition according to claim 7, wherein the composition is a food. 13.A method for preventing or improving dementia, comprising administeringto a subject in need thereof an effective amount of a compositioncomprising one or more kinds of essential amino acids other than leucineand not less than 35 mol % of leucine, relative to the total content ofessential amino acids.
 14. The method according to claim 13, whereinsaid composition comprises said leucine in an amount of 35 mol % to 66mol %, relative to the total content of essential amino acids.
 15. Themethod according to claim 13, wherein said one or more kinds ofessential amino acids other than leucine are isoleucine, valine,threonine, lysine, methionine, histidine, phenylalanine, and tryptophan.16. The method according to claim 15, wherein a molar composition ratioof the content of each amino acid in said composition, relative to thetotal content of essential amino acids, falls within the followingnumerical values: leucine: 35 mol % to 66 mol % isoleucine: 5 mol % to15 mol % valine: 5 mol % to 15 mol % threonine: 7 mol % to 14 mol %lysine: 8 mol % to 16 mol % methionine: 2 mol % to 10 mol % histidine:0.1 mol % to 3.5 mol % phenylalanine: 2.5 mol % to 8 mol % tryptophan:0.1 mol % to 2 mol %.
 17. The method according to claim 13, whichprevents or improves a memory disorder.
 18. The method according toclaim 13, which suppresses a decline of cognitive function or improvescognitive function.
 19. The method according to claim 13, wherein thedementia is Alzheimer-type dementia.
 20. A method for preventing orimproving a depressive state, comprising administering to a subject inneed thereof an effective amount of a composition comprising one or morekinds of essential amino acids other than leucine and not less than mol% of leucine, relative to the total content of essential amino acids.21. The method according to claim 20, wherein said composition comprisessaid leucine in an amount of 35 mol % to 66 mol %, relative to the totalcontent of essential amino acids.
 22. The method according to claim 20,wherein said one or more kinds of essential amino acids other thanleucine are isoleucine, valine, threonine, lysine, methionine,histidine, phenylalanine, and tryptophan.
 23. The method according toclaim 22, wherein a molar composition ratio of the content of each aminoacid in said composition, relative to the total content of essentialamino acids, falls within the following numerical values: leucine: 35mol % to 66 mol % isoleucine: 5 mol % to 15 mol % valine: 5 mol % to 15mol % threonine: 7 mol % to 14 mol % lysine: 8 mol % to 16 mol %methionine: 2 mol % to 10 mol % histidine: 0.1 mol % to 3.5 mol %phenylalanine: 2.5 mol % to 8 mol % tryptophan: 0.1 mol % to 2 mol %.24. The method according to claim 20, wherein said depressive state is adepressive state caused by stress.